Helical gear



FIG. 1 is a first perspective view of a helical gear showing my new design;

FIG. 2 is a second perspective view of the helical gear;

FIG. 3 is a front view of the helical gear;

FIG. 4 is a top view of the helical gear; and,

FIG. 5 is a bottom view of the helical gear. 

CLAIM The ornamental design for a helical gear, as shown and described. 